Subtracting two numbers without using '-' operator

Question

i tried with the following code , but i can\'t understand why it\'s giving me wrong answer. i am computing the 2\'s complement and adding with another no.

#inclu         


        

Answer 1

import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.xml.soap.Node;

public class mainone {





 public static void main(String args[]){


 int a=12;
 int b=4;
 Integer  c=new Integer(b);
 String  d=Integer.toString(c);
 String e="-";
 String f=e.concat(d);
 Integer g=Integer.parseInt(f);
 System.out.println(a+g);





 }



 }